fix(ivy): pipes are pure by default (#24750)

PR Close #24750

packages/compiler-cli/src/ngtsc/annotations/src/pipe.ts

@@ -50,7 +50,7 @@ export class PipeDecoratorHandler implements DecoratorHandler<R3PipeMetadata> {
     }
     this.scopeRegistry.registerPipe(clazz, pipeName);
 
-    let pure = false;
+    let pure = true;
     if (pipe.has('pure')) {
       const pureValue = staticallyResolve(pipe.get('pure') !, this.checker);
       if (typeof pureValue !== 'boolean') {

packages/compiler-cli/test/ngtsc/ngtsc_spec.ts

@@ -270,6 +270,31 @@ describe('ngtsc behavioral tests', () => {
     expect(dtsContents).toContain('static ngPipeDef: i0.ɵPipeDef<TestPipe, \'test-pipe\'>;');
   });
 
+  it('should compile pure Pipes without errors', () => {
+    writeConfig();
+    write('test.ts', `
+        import {Pipe} from '@angular/core';
+
+        @Pipe({
+          name: 'test-pipe',
+        })
+        export class TestPipe {}
+    `);
+
+    const exitCode = main(['-p', basePath], errorSpy);
+    expect(errorSpy).not.toHaveBeenCalled();
+    expect(exitCode).toBe(0);
+
+    const jsContents = getContents('test.js');
+    const dtsContents = getContents('test.d.ts');
+
+    expect(jsContents)
+        .toContain(
+            'TestPipe.ngPipeDef = i0.ɵdefinePipe({ name: "test-pipe", type: TestPipe, ' +
+            'factory: function TestPipe_Factory() { return new TestPipe(); }, pure: true })');
+    expect(dtsContents).toContain('static ngPipeDef: i0.ɵPipeDef<TestPipe, \'test-pipe\'>;');
+  });
+
   it('should compile Pipes with dependencies', () => {
     writeConfig();
     write('test.ts', `